Cell Membranes Movement Across Them Regents Biology 2006
Cell Membranes & Movement Across Them Regents Biology 2006 -2007
DO NOW § Do you smell the popcorn? § Do you see the pink stuff slowly moving in the cell? v. What do these two occurrences have in common? v. Make a list with a partner of other everyday occurrences that happen for the same reason. Regents Biology
Cellular Transport 1. Processes involved: a. b. Absorption – To take in, substances must pass through the cell membrane Circulation – movement of materials inside a cell or around an organism Regents Biology
2. Cell Membrane Structure a. Phospholipid bilayer – proteins, lipids, carbohydrates. b. Fluid Mosaic Model – lipid layers are in a constant flexible, fluid state. Regents Biology
Lipids of cell membrane § Membrane is made of special kind of lipid u u phospholipids “split personality” “attracted to water” § Membrane is a double layer u phospholipid bilayer phosphate inside cell lipid outside cell Regents Biology “repelled by water”
2. Cell Membrane Structure c. Selectively Permeable i. ii. iii. Some substances CAN pass through Some can only pass through AT CERTAIN TIMES Some CANNOT pass through So what needs to get across the membrane? sugar Regents Biology lipids aa O 2 H 2 O salt waste
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Transport Vocabulary Solution – mixture of solvent + solute (Saltwater Solution) Solute – dissolved particles (Salt) Solvent – liquid that dissolves solute (Water) Regents Biology
Passive Transport (Diffusion) 1. Diffusion – movement across a membrane Concentration gradient – high to low Concenration Gradient: b. Moves across gradient until equilibrium is reached a. O N Y G R E EN !!! Regents Biology
Simple Diffusion § Move from HIGH to LOW fat inside cell fat LOW fat fat Which way will fat move? HIGH outside cell fat fat fat Regents Biology fat fat
Passive Transport (Diffusion) 2. Osmosis – Diffusion of Water across a membrane Water Salt 100% W 5% S 95% W Regents Biology
Regents Question Regents Biology
Regents Question Regents Biology
Regents Question Regents Biology
Turgor Plasmolysis Regents Biology
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Let’s Apply this to a Real Situation § What causes human blood cells to swell or shrink? Regents Biology
Hypertonic Solution § When the solution inside the blood cell § has a high solute concentration than its environment, the cell is said to be hypertonic to its environment. Water will diffuse in. The cell cannot get rid of the water fast enough, and the cell swells and lysis. Regents Biology
Hypotonic Solution § When the solution inside the cell has a § lower concentration of solute than its environment, the cell is said to be hypotonic to its environment. Water will diffuse out of the cell, causing the cell to shrink or crenate. Regents Biology
Isotonic Solution § When the solute concentration outside the cell is equal to the solute concentration inside the cell, the cell retains its shape. Regents Biology
DO NOW § Movie Madness § What does your mouth feel like before § § § eating salty movie popcorn? What does your mouth feel like after eating the popcorn? Why do you think this occurs? Hint: Think about what is happening to the cells inside your mouth. Why do you think movie theaters put a lot of salt on their popcorn? Regents Biology
Practice § Why is the water leaving the cell? § The cell is hypotonic to the environment. § What must be done to allow the water to reenter the cell? 3% salt 5% salt § Dilute the outside salt concentration by adding water § What does the 3 and 5 % represent? § Regents Biology solute
Crossing the cell membrane § What molecules can get through the cell membrane directly? u Fats, oils, and very small molecules lipid inside cell salt waste outside cell Regents Biology sugar aa H 2 O but… what about other stuff?
FACILITATED DIFFUSION: § Need “doors” through membrane u protein channels allow substances in & out that cannot cross otherwise § specific channels allow specific material in & out § Ex. H 2 O channel, salt channel, sugar channel, etc. inside cell H 2 O salt waste Regents Biology aa sugar outside cell
Facilitated Diffusion § Move from HIGH to LOW through a channel sugar inside cell sugar sugar LOW Which way will sugar move? HIGH outside cell sugar Regents Biology sugar sugar
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Active Transport 1. Requires the use of energy (ATP) 2. Movement is against the concentration gradient (low to high) Concentration Gradient: S E R I U REQ GY!!! R E EN Regents Biology
Active Transport 3. Types: a. Pinocytosis – cell membrane engulfs small amounts of liquid Regents Biology b. Phagocytosis – solid particles are engulfed by cell.
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Regents Question Cyanide is a poison that limits the ability of an animal cell to manufacture ATP. In a cell containing a small amount of cyanide, which process would be least affected? 1. Cell division 3. movement 2. Active transport 4. diffusion Regents Biology
Cellular Transport REVIEW 1) What is meant by the fluid-mosaic model? 2) Define diffusion. 3) How are diffusion and osmosis similar? Different? 4) How are diffusion and active transport different? List 2 ways. Regents Biology
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